TW201523726A - Fluorocarbon based aspect-ratio independent etching - Google Patents

Abstract

A method for etching features into an etch layer disposed below a patterned mask is provided. At least three cycles are provided, where each cycle comprises providing an ion bombardment, by creating a plasma, of the etch layer to create activated sites of surface radicals in parts of the etch layer exposed by the patterned mask, extinguishing the plasma, exposing the etch layer to a plurality of fluorocarbon containing molecules, which causes the bound fluorocarbon containing molecules to selectively bind to the activated sites, wherein the selective binding is self limiting, and providing an ion bombardment of the etch layer to initiate an etch reaction between the fluorocarbon containing molecule and the etch layer, wherein the ion bombardment of the etch layer to initiate an etch reaction causes the formation of volatile etch products formed from the etch layer and the bound fluorocarbon containing molecules.

Description

Non-dependent aspect ratio etching based on fluorocarbons

The present invention relates to a method of forming a semiconductor component on a semiconductor wafer. More specifically, the present invention relates to etching a layer in the formation of a semiconductor element.

In forming a semiconductor component, certain components can be etched to provide wide and narrow features.

In order to achieve the foregoing and in accordance with the purpose of the present invention, a method for etching features into an etch layer disposed under a patterned mask is provided. Providing at least three cycles, wherein each cycle comprises the steps of: providing ion bombardment of the etch layer by generating a plasma to create an active site of surface free radicals in a portion of the etch layer exposed by the patterned mask; Extinguishing the plasma; exposing the etch layer to molecules of a plurality of fluorocarbon compounds, which cause the molecules of the fluorocarbon compound to selectively bind to the active site, wherein the selective bonding process is self-limiting; And providing ion bombardment of the etch layer to cause an etch reaction between the molecules of the fluorocarbon compound and the etch layer, wherein ion bombardment of the etch layer to cause an etch reaction results in formation of a volatile etch product, The volatile etching product is formed by the etching layer and molecules of the fluorine-containing carbon compound.

In another manifestation of the invention, a method for etching features into an etch layer disposed under a patterned mask is provided. Providing at least one cycle, wherein each cycle comprises the steps of: providing ion bombardment of the etch layer to create an active site in a portion of the etch layer exposed by the patterned mask; exposing the etch layer to a plurality of a molecule of a fluorocarbon compound, the molecules of the fluorine-containing carbon compound being selectively bonded to an active site, wherein the selective bonding process is self-limiting; and providing ion bombardment of the etching layer to cause a fluorine-containing carbon compound An etching reaction between the molecules and the etch layer.

These and other features of the present invention will be described in more detail in the following detailed description of the invention.

The invention will now be described in detail with reference to a number of preferred embodiments of the invention as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth to provide a comprehensive understanding of the invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in the absence of some or all of these specific details. In other instances, well-known process steps and/or structures are not described in detail to avoid unnecessarily obscuring the invention.

1 is a high level flow diagram of an embodiment of the present invention. In this embodiment, the substrate is placed in an etch chamber (step 104). Preferably, the substrate has an etch layer disposed beneath the patterned mask. The etch layer is etched using an atomic layer etch using a fluorocarbon (step 108). Such etching involves a cyclic process. In each cycle, an active site is generated (step 112). Ion bombardment of the exposed portion of the etch layer creates an active site in the etch layer. The active site is exposed to molecules of the fluorocarbon compound (step 116), resulting in some molecules attached to the active site. An etching reaction between the fluorocarbon compound and the etch layer is caused by ion bombardment (step 120). It is determined whether the loop is repeated (step 124). The substrate is removed from the chamber (step 128). example

In a preferred embodiment of the invention, the substrate is placed in an etch chamber (step 104) having an etch layer of ruthenium oxide disposed under the patterned mask. 2A is a schematic cross-sectional view of a stack 200 having a substrate 204 having an etch layer 208 disposed beneath the patterned mask 212. In this example, one or more layers may be disposed between the substrate 204 and the etch layer 208 or between the etch layer 208 and the patterned mask 212. In this example, the patterned mask 212 is polysilicon and the etch layer 208 is a cerium oxide based dielectric. Other embodiments may use other primary masking materials such as spin-coated organic mask layers and alpha-C (amorphous carbon layer (ACL)). In this example, the mask pattern feature 220 has been formed in the patterned mask 212. In some embodiments, the mask pattern features 220 are formed prior to placing the substrate 204 in the chamber. In other embodiments, the mask pattern feature 220 is formed when the substrate 204 is in the chamber. As shown, some of the mask pattern features 220 may be wider than the other mask pattern features 220. Width is not the only factor that affects shading, and the shape of the hole is also very important. In this example, one mask pattern feature 220 is several times wider than the other mask pattern feature 220.

3 is a schematic illustration of a plasma processing chamber 300 that can be used in one or more of the following steps. The plasma processing chamber 300 includes a confinement ring 302, an upper electrode 304, a lower electrode 308, a gas source 310, and a drain pump 320. Within the plasma processing chamber 300, the substrate 204 is positioned over the lower electrode 308. The lower electrode 308 includes a suitable substrate holding mechanism (eg, an electrostatic clamp, a mechanical clamp, etc.) for holding the substrate 204. Reactor top 328 includes an upper electrode 304 disposed directly relative to lower electrode 308. Upper electrode 304, lower electrode 308, and confinement ring 302 define a limited plasma volume 340. Gas is supplied to the restricted plasma volume 340 through the gas inlet 343 by the gas source 310, and the gas is discharged from the restricted plasma volume 340 through the confinement ring 302 and the discharge port by the discharge pump 320. In addition to assisting in the venting of the gases, the bleed pump 320 also assists in regulating the pressure. In this embodiment, gas source 310 includes argon source 312, fluorocarbon gas source 316, and additional gas source 318. Gas source 310 may further comprise other sources of gas. The RF source 348 is electrically coupled to the lower electrode 308. The chamber wall 352 surrounds the confinement ring 302, the upper electrode 304, and the lower electrode 308. It is possible to connect RF power to the electrode system in different combinations. In a preferred embodiment, the 27 MHz, 60 MHz, and 2 MHz power sources make up the RF power source 348 that is connected to the lower electrode 308, while the upper electrode 304 is grounded. Controller 335 is controllably coupled to RF source 348, drain pump 320, and gas source 310. Preferably, the processing chamber 300 is a capacitively coupled plasma (CCP) reactor as shown. In other embodiments, an inductive coupled plasma (ICP) reactor or other source may be used, such as surface waves, microwaves, or electron cyclotron resonance (ECR).

4 is a high level block diagram showing computer system 400 suitable for implementing controller 335 for use in embodiments of the present invention. This computer system can take many physical forms, ranging from integrated circuits, printed circuit boards, and small handheld devices to giant supercomputers. The computer system 400 includes one or more processors 402, and may further include an electronic display device 404 (for displaying images, text, and other materials), a main memory 406 (eg, random access memory (RAM) Memory)), storage device 408 (such as a hard disk drive), removable storage device 410 (such as a CD player), user interface device 412 (such as a keyboard, touch screen, keypad, mouse or other pointing device, etc.) ), and a communication interface 414 (eg, a wireless network interface). Communication interface 414 allows software and data to be transferred between computer system 400 and external devices via a connection. The system can also include a communication infrastructure 416 (e.g., a communication bus, a cross-over bar, or a network) coupled to the devices/modules described above.

The information transmitted via the communication interface 414 may be in the form of, for example, electronic, electromagnetic, optical, or other signals that can be received by the communication interface 414 via a communication link that can transmit signals and can use wires or cables. , fiber optics, telephone lines, mobile phone connections, RF connections, and/or other communication conduits. With such a communication interface, it is contemplated that one or more processors 402 may receive information from the network during the execution of the method steps described above, or may output information to the network. In addition, the method embodiment of the present invention may be performed only on a processor or may be performed through a network (such as the Internet), which is associated with a remote processor sharing a part of the processing program. connection.

The term "non-transient computer readable medium" is generally used to mean a medium such as a main memory, a secondary memory, a removable storage, and a storage device, such as a hard device. Discs, flash memory, disk memory, CD-ROM, and other forms of permanent memory, and non-transitory computer readable media should not be interpreted as covering transient objects such as carriers or signals. Examples of computer code include machine code (such as those produced by the compiler) and files containing higher-level code that is executed by the computer using an interpreter. The computer readable medium can also be a computer code that is transmitted by a computer data signal contained in the carrier and represents a series of instructions executable by the processor.

After the substrate 204 has been placed into the plasma processing chamber 300, the etch layer 208 is etched by atomic layer etching (step 108). Ion bombardment is used to generate an active site (step 112). In this example, Ar plasma was used by providing a pressure of 50 mT and flowing 800 sccm of Ar into the chamber. An RF input of 400 W at 60 MHz and 100 W at 27 MHz is provided to excite Ar. Maintain the wafer temperature at 20 °C. This process is maintained for 3 seconds. 2B is a schematic cross-sectional view of a stack 200 having a substrate 204 having an etch layer 208 disposed beneath the patterned mask 212 during generation of active sites 216 by argon ion bombardment 228. After the active site 216 is generated, the argon ion bombardment 228 is stopped. The layer of active site 216 can be very thin, but it is not drawn to scale to show active site 216. Due to the directionality of ion bombardment, the active sites are preferentially produced on a horizontal surface comprising the surface of the etch layer 208, the surface of the mask layer 217. The sidewalls of feature 218 are minimally activated because the ion flux is relatively low and the energy transfer from ion collisions is relatively low.

The etch layer 208 is then exposed to a deposition gas comprising molecules of the fluorocarbon compound (step 116). In this example, 1,3-hexafluorobutadiene (1-C4F6) was introduced at a flow rate of 20 sccm for 3 seconds at a pressure of 10 mT, a wafer temperature of 20 ° C, and no RF excitation. 2C is a schematic cross-sectional view of a stack 200 having a substrate 204 having an etch layer 208 disposed beneath the patterned mask 212 after exposure to molecules of the fluorocarbon compound. The molecules of the fluorocarbon compound adhere to the active site 216, and the molecules of the fluorocarbon compound are selectively deposited on the active site 216 to form a selective and self-limiting deposition of the 232 of the fluorocarbon compound. . Due to the nature of the selectivity of the deposition, very few molecules of the fluorocarbon will adhere to the sidewalls with very few active sites. After the active site is occupied by molecules of the fluorocarbon compound, this site is less active for the molecules of the subsequent fluorocarbon compound, resulting in a self-limiting surface coverage of the molecules of the fluorocarbon compound. At the exposed surface of the etch layer, there is a mixed layer of molecules 232 of fluorine-containing carbon compound and active sites 216. Below the mixed layer is an etch layer 208. Since the deposition of molecules of the fluorocarbon compound is selective and self-limiting, a layer of almost uniform thickness of the molecules of the fluorocarbon compound is deposited on the bottom of the feature without the feature width and/or depth. Than the impact.

An etching reaction is caused between the molecules of the fluorocarbon compound and the etch layer (step 120). In this embodiment, ion bombardment is used to cause an etching reaction. In this example, the same formulation as described above for the activator can be used herein. 2D is a schematic cross-sectional view of a stack 200 having a substrate 204 having an etch layer 208 disposed under the patterned mask 212 during bombardment of 236 by argon ions to cause an etch reaction. In this example, ion bombardment causes the fluorocarbon molecules to react with the etch layer to produce volatile products 238 from the molecules of the fluorocarbon compound and the components of the etch layer. Some of the volatile products 238 from the etching reaction may be SiF ₄ , SiF ₂ , CO ₂ , and CO. The reaction is limited by the amount of fluorocarbon deposited. By providing a uniform thickness or amount of molecules of the deposited fluorocarbon compound on the surface of the etch layer, the amount of etching between features having different widths or aspect ratios can be made more uniform. Preferably, the entire mixed layer is etched away. At the end of this cycle, partially etched features 240 are formed.

The etch cycle (step 124) can then be repeated as needed to increase the progress of the etch. After the etching step is performed for a plurality of cycles, the etching is completed. 2E is a schematic cross-sectional view of a stack 200 having a substrate 204 (having an etch layer 208) after etching of the features 240.

Since the activation by ion bombardment is highly directional and the deposition of fluorocarbons is self-limiting, the resulting etching system and geometry, aspect ratio, critical dimension (CD), and depth It is highly uncorrelated and has minimal variations in wafer uniformity and wafer-to-wafer repeatability. Although the preferred embodiment described above provides dielectric etching to etch the dielectric etch layer, in other embodiments, fluorocarbon etching may be used to etch other materials. By using molecules of the undissociated fluorocarbon compound, the selectivity and self-limiting of the deposition of the fluorocarbon can be increased. Such molecules are more likely to adhere to the active site in a self-limiting manner and are less likely to adhere to unactivated sites, increasing selectivity and independence of aspect ratio. In the above embodiments, the exposure and deposition of the fluorocarbon are plasmaless so that the molecules of the undissociated fluorine-containing carbon compound are maximized. In order to reduce the exposure of the etch layer to molecules of the dissociated or ionized fluorocarbon compound, a pumping and/or scavenging step may be provided to unbond the activity prior to subsequent plasma ion bombardment to cause a chemical reaction. Molecular removal of any residual fluorocarbon compounds at the site.

The use of 1,3-hexafluorobutadiene as a molecule of a fluorine-containing carbon compound provides a fluorocarbon compound having sufficient reactivity. Other embodiments may use hexafluoropropylene oxide (C ₃ F ₆ O) or C ₂ F ₄ as the molecule of the fluorine-containing carbon compound.

In other embodiments, selective deposition of molecules of the fluorocarbon compound can occur as an exchange reaction, such that a portion of the original molecule is joined to the surface active site and another portion of the initial molecule exits the surface as a stable gas phase species. Such an embodiment of a molecular-based C ₃ F ₆ O, which may interact with the surface active sites formed by C ₂ F ₄ O (vapor species), and CF ₂ (bonded to the surface). In this example, the molecules of the undissociated C ₃ F ₆ O fluorocarbon compound are exposed to the etch layer, and only the CF ₂ moiety of the molecule is bonded to the active site. Thus, larger molecules containing fluorocarbon, the active sites which will react with the fluorocarbon-containing molecule to produce the selectively bonded to the active site of the C ₃ F ₆ O is based.

In other embodiments, a low density plasma may be provided in situ or downstream to provide some molecules of the dissociated fluorocarbon compound. In this low density plasma, the efficiency with which electrons dissociate the gas is low. In the context of this specification and the patent application, a low density plasma is defined as an electron density between 10 ⁷ and 10 ⁹ electrons per cm ³ . In addition, the temperature in the electrons is less than 4 eV. In one embodiment, the downstream source is used to cleave the gas of the fluorocarbon compound away from the wafer and thereby allow it to recombine into a fluorocarbon having an ideal reactivity (lower reactivity than the direct plasma species). Compound species. For example, downstream cC ₄ F ₈ can produce a higher proportion of CF ₂ and C ₂ F ₄ (which is desirable), and a lower proportion of other fluorocarbon free radicals (which tend to be non-selective) Sexual deposition is therefore less enjoyable).

In certain embodiments, the plasma is extinguished after ion bombardment and prior to exposing the etch layer to molecules of the fluorocarbon compound to increase the molecules of the undissociated fluorocarbon compound reacted at the active site. percentage. More preferably, most of the molecules of the fluorocarbon compound that arrive at the active site are not dissociated.

In one embodiment, a single monolayer of fluorocarbon compound molecules are attached to the etch layer prior to activating the etch reaction. Such an embodiment may etch only a corresponding thickness of the etch layer in each cycle. The amount etched is proportional to the amount deposited, as defined by the stoichiometry of the etch reaction and the limitations of the etch stop when the fluorocarbon is completely depleted. In other embodiments, molecules of a plurality of layers of fluorocarbon compounds may be attached or deposited on the etch layer, possibly due to transfer of surface active sites to new active sites within the attached molecule, and subsequent additional The molecules of the fluorocarbon are attached to these new active sites. These embodiments etch the etch layer to a corresponding thickness, which is again defined by stoichiometry and fluorocarbon consumption. These embodiments provide a self-limiting embodiment of such deposition, such that even if more than one molecular layer of fluorocarbon molecules are deposited, such deposition is self-limiting and therefore the amount deposited will not exceed a limit. thickness. Since the pair of sites on adjacent molecular chains will react and produce a terminating ring structure, it is expected that the end of the self-sustaining molecular active site will eventually occur. In this way, a plurality of layers of fluorocarbon molecules can be deposited while providing self-limiting deposition. The thickness of the molecules of the deposited fluorine-containing carbon compound must be sufficiently small to allow the ion activation reaction to proceed in the next step. The specific limits of this thickness depend on the mass, species, and energy of the bombardment ions. Preferably, the deposition of the molecules of the self-limiting fluorocarbon compound deposits a layer of no more than 6 nm. More preferably, the deposition of molecules of this self-limiting fluorocarbon compound deposits a layer of no more than 3 nm.

In various embodiments, the molecules of the fluorocarbon compound may have other elemental components such as hydrogen, nitrogen, and/or oxygen. These ingredients may be useful for increasing the reactivity of the molecule with surface active sites. The carbon component of the molecules of the fluorocarbon compound is required to provide etch selectivity to more selectively etch the target etch layer relative to other layers (eg, patterned mask or etch stop layer). A fluorine component is required to provide the ability to remove the germanium etch in the target etch layer. In other embodiments, etching and surface activation step, the use of other gases such as Ne, Xe, or N ₂ instead of argon. Preferably, such bombardment ions should not cause deposition after surface fluorocarbon depletion and do not significantly etch the etch layer.

In general, the thickness of the fluorocarbon deposit on the bottom of the different features varies by less than 2:1, wherein the aspect ratio of the features can vary by as much as 0.1 to 10. The self-limiting embodiment of fluorocarbon deposition allows for more uniform selective deposition.

Although in the above embodiments, ion bombardment of the etch layer is provided to cause an etch reaction between the fluorocarbon compound and the etch layer, and ion bombardment of the etch layer is provided to expose the etch layer by the patterned mask The generation of active sites in portions is an individual step, but in other embodiments they may be the same step that uses a bombardment to sequentially and/or simultaneously cause an etch reaction and generate an active site.

If the process is carried out with ion bombardment sufficient to produce a surface active site, but insufficient to cause an etch reaction, a net atomic layer deposition of the molecules of the fluorocarbon compound will result. This net atomic layer deposition may occur if the ion activation step is capable of producing an active site without causing an etch reaction.

If a plasma of a molecule of a fluorocarbon compound is used in the fluorocarbon exposure step 116, some of the molecules of the fluorocarbon compound will dissociate to form a fluorocarbon radical which will attach to the surface of the etched layer without The active site, and thus such deposition, is not self-limiting, less selective, and will be more dependent on the feature width due to the shadowing effect. During the atomic layer etch cycle, more etching occurs in the wider or lower aspect ratio features than in the narrower or higher aspect ratio features due to the geometry of the features.

While the invention has been described in terms of several preferred embodiments, modifications, variations, substitutions, and various alternatives are possible within the scope of the invention. It should also be noted that there are many alternative ways of implementing the methods and apparatus of the present invention. Therefore, it is intended that the appended claims be interpreted as including all such modifications, modifications,

104 ~ 128‧‧‧Steps
200‧‧‧Stacking
204‧‧‧Substrate
208‧‧‧etching layer
212‧‧‧ patterned mask
216‧‧‧Active sites
217‧‧‧ mask layer
218‧‧‧ Characteristic Department
220‧‧‧Mask pattern features
228‧‧‧Argon bombardment
232‧‧ ‧ molecules of fluorocarbons
236‧‧‧argon bombardment
238‧‧‧ volatile products
240‧‧‧Characteristic Department
300‧‧‧(plasma) processing chamber
302‧‧‧Restricted ring
304‧‧‧Upper electrode
308‧‧‧ lower electrode
310‧‧‧ Gas source
312‧‧‧ source of argon
316‧‧‧Fluorine-containing gas source
318‧‧‧Additional gas source
320‧‧‧Drain pump
328‧‧‧reactor top
335‧‧‧ Controller
340‧‧‧Restricted plasma volume
343‧‧‧ gas inlet
348‧‧‧RF (power) source
352‧‧‧ chamber wall
400‧‧‧ computer system
402‧‧‧Processor
404‧‧‧Electronic display device
406‧‧‧ main memory
408‧‧‧ storage device
410‧‧‧Removable storage device
412‧‧‧User interface device
414‧‧‧Communication interface
416‧‧‧Communication infrastructure

The present invention is shown by way of example, and not limitation, FIG.

1 is a high level flow diagram of an embodiment of the present invention.

2A-E are schematic cross-sectional views of a stack processed in accordance with an embodiment of the present invention.

3 is a schematic illustration of a plasma processing chamber that can be used in one embodiment of the present invention.

4 is a schematic illustration of a computer system that can be used to implement the present invention.

104~128‧‧‧Steps

Claims (19)

A method for etching features into an etch layer, the etch layer being disposed under a patterned mask, the method comprising performing at least three cycles, wherein each cycle comprises the steps of: providing by generating a plasma Ion bombardment of the etch layer to generate a plurality of active sites in a portion of the etch layer exposed by the patterned mask; extinguishing the plasma; exposing the etch layer to a plurality of fluorocarbon compounds a molecule that causes the molecules of the plurality of fluorocarbon compounds to selectively bind to the active sites, wherein the selective bonding process is self-limiting; and providing ion bombardment of the etch layer to cause such An etching reaction between a molecule of a fluorocarbon compound and the etch layer, wherein ion bombardment of the etch layer to cause an etch reaction results in formation of a volatile etch product from the etch layer and the Formed by molecules such as fluorine-containing carbon compounds. The method for etching a feature into an etch layer as described in claim 1, further comprising the step of: after exposing the etch layer to a molecule of the plurality of fluorocarbon compounds The molecules of the unbonded fluorocarbon compound are removed prior to ion bombardment of the etch layer to cause an etch reaction. A method for etching a feature into an etch layer as described in claim 1, wherein the fluorocarbon compound of the plurality of fluorocarbon molecules is provided as a plurality of gases a portion of a molecule of a larger fluorocarbon compound in a molecule of a fluorocarbon compound, wherein molecules of the larger fluorocarbon compound react with the active sites to produce molecules of the fluorocarbon compound, It selectively binds to the active sites. A method for etching features into an etch layer, the etch layer being disposed under a patterned mask, the method comprising performing at least one cycle, wherein each cycle comprises the steps of: providing ion bombardment of the etch layer, Generating a plurality of active sites in a portion of the etch layer exposed by the patterned mask; exposing the etch layer to molecules of a plurality of fluorocarbon compounds, the molecules of the fluorocarbons being selectively selected Bonding to the active sites, wherein the selective bonding process is self-limiting; and providing ion bombardment of the etch layer to cause an etch reaction between the molecules of the fluorocarbon compound and the etch layer. A method for etching a feature into an etch layer as described in claim 4, wherein ion bombardment of the etch layer to cause an etch reaction results in formation of a volatile etch product, the volatility etch The product is formed from the etch layer and molecules of the fluorocarbon compounds. A method for etching a feature into an etch layer as described in claim 5, wherein the step of exposing the etch layer to a plurality of fluorocarbon molecules is performed by exposing the etch layer This is done by the molecule of the undissociated fluorocarbon compound. A method for etching a feature into an etch layer as described in claim 6 wherein the step of providing ion bombardment of the etch layer to generate a plurality of active sites is performed by generating a plasma Completed, and further comprising the step of extinguishing the plasma after providing the ion bombardment to generate a plurality of active sites and before exposing the etch layer to molecules of the plurality of fluorocarbon compounds. A method for etching a feature into an etch layer as described in claim 7 wherein the ion bombardment provides an argon ion bombardment. The method for etching a feature into an etch layer as described in claim 7 further includes the step of: after exposing the etch layer to the molecules of the plurality of fluorocarbon compounds and providing the The molecules of the unbonded fluorocarbon compound are removed prior to ion bombardment of the etch layer. A method for etching a feature into an etch layer as described in claim 7 wherein the molecules of the fluorocarbon compound comprise 1,3-hexafluorobutadiene. A method for etching a feature into an etch layer as described in claim 7 wherein the generation of an active site causes surface free radicals. A method for etching a feature into an etch layer as described in claim 7 wherein the molecules of the fluorocarbon compound comprise hexafluoropropylene oxide (C ₃ F ₆ O). A method for etching a feature into an etch layer as described in claim 4, wherein ion bombardment of the etch layer is provided to cause a molecule between the fluorocarbon compound and the etch layer The step of etching the reaction, and the step of providing ion bombardment of the etch layer to produce a plurality of active sites in the portion of the etch layer exposed by the patterned mask, is an individual step. A method for etching a feature into an etch layer as described in claim 4, wherein ion bombardment of the etch layer is provided to cause a molecule between the fluorocarbon compound and the etch layer The step of etching the reaction, and the step of providing ion bombardment of the etch layer to produce a plurality of active sites in the portion of the etch layer exposed by the patterned mask, is the same step. A method for etching a feature into an etch layer as described in claim 4, wherein the at least one cycle is at least ten cycles. A method for etching a feature into an etch layer as described in claim 4, wherein the step of exposing the etch layer to a plurality of fluorocarbon molecules is performed by exposing the etch layer This is done by the molecule of the undissociated fluorocarbon compound. A method for etching a feature into an etch layer as described in claim 4, wherein the step of providing ion bombardment of the etch layer to generate a plurality of active sites is performed by generating a plasma Completed, and further comprising the step of extinguishing the plasma after providing the ion bombardment to generate a plurality of active sites and before exposing the etch layer to molecules of the plurality of fluorocarbon compounds. The method for etching a feature into an etch layer as described in claim 4, further comprising the step of: after exposing the etch layer to a molecule of the plurality of fluorocarbon compounds The molecules of the unbonded fluorocarbon compound are removed prior to ion bombardment of the etch layer. A method for etching a feature into an etch layer as described in claim 4, wherein the molecular structure of the fluorocarbon compound of the plurality of fluorocarbon molecules is a plurality of gases provided as a gas a portion of a molecule of a larger fluorocarbon compound in a molecule of a fluorocarbon compound, wherein molecules of the larger fluorocarbon compound react with the active sites to produce molecules of the fluorocarbon compound, It selectively binds to the active sites.